/**
 *    Copyright (C) 2014 MongoDB Inc.
 *
 *    This program is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the GNU Affero General Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

#pragma once

#include <string>

#include "mongo/db/json.h"
#include "mongo/db/storage/mmap_v1//btree/btree_logic.h"
#include "mongo/db/storage/mmap_v1/heap_record_store_btree.h"
#include "mongo/db/storage/mmap_v1/record_store_v1_test_help.h"


namespace mongo {

    /**
     * Generates a string of the specified length containing repeated concatenation of the
     * hexadecimal representation of the input value.
     */
    std::string bigNumString(long long n, int len);

    /**
     * Generates key on a field 'a', with the specified number of repetitions of the character.
     */
    BSONObj simpleKey(char c, int n = 1);

    /**
     * Simple head manager, which performs no validity checking or persistence.
     */
    class TestHeadManager : public HeadManager {
    public:
        virtual const DiskLoc getHead( OperationContext* txn ) const {
            return _head;
        }

        virtual void setHead(OperationContext* txn, const DiskLoc newHead) {
            _head = newHead;
        }

    private:
        DiskLoc _head;
    };


    /**
     * This structure encapsulates a Btree and all the infrastructure needed by it (head manager,
     * record store and a valid disk location to use by the tests).
     */
    template <class OnDiskFormat>
    struct BtreeLogicTestHelper {
        BtreeLogicTestHelper(const BSONObj& order);

        // Everything needed for a fully-functional Btree logic
        TestHeadManager headManager;
        HeapRecordStoreBtree recordStore;
        BtreeLogic<OnDiskFormat> btree;
        DiskLoc dummyDiskLoc;
    };


    /**
     * Tool to construct custom tree shapes for tests.
     */
    template <class OnDiskFormat>
    class ArtificialTreeBuilder {
    public:

        typedef typename BtreeLogic<OnDiskFormat>::BucketType BucketType;
        typedef typename BtreeLogic<OnDiskFormat>::KeyDataOwnedType KeyDataOwnedType;
        typedef typename BtreeLogic<OnDiskFormat>::KeyHeaderType KeyHeaderType;

        typedef typename OnDiskFormat::FixedWidthKeyType FixedWidthKeyType;

        /**
         * The tree builder wraps around the passed-in helper and will invoke methods on it. It 
         * does not do any cleanup, so constructing multiple trees over the same helper will
         * cause leaked records.
         */
        ArtificialTreeBuilder(OperationContext* txn,
                              BtreeLogicTestHelper<OnDiskFormat>* helper)
            : _txn(txn), _helper(helper) {

        }

        /**
         * Causes the specified tree shape to be built on the associated helper and the tree's
         * root installed as the head. Uses a custom JSON-based language with the following 
         * syntax:
         *
         * Btree := BTreeBucket
         * BtreeBucket := { Child_1_Key: <BtreeBucket | null>, 
         *                  Child_2_Key: <BtreeBucket | null>, 
         *                  ...,
         *                  _: <BtreeBucket | null> }
         *
         * The _ key name specifies the content of the nextChild pointer. The value null means 
         * use a fixed disk loc.
         */
        void makeTree(const std::string& spec);

        /**
         * Validates that the structure of the Btree in the helper matches the specification.
         */
        void checkStructure(const std::string& spec) const;

        /**
         * Adds the following key to the bucket and fixes up the child pointers.
         */
        void push(const DiskLoc bucketLoc, const BSONObj& key, const DiskLoc child);

        /**
         * @return The number of keys inserted.
         */
        int fillBucketToExactSize(const DiskLoc bucketLoc, int targetSize, char startKey);

    private:
        DiskLoc makeTree(const BSONObj& spec);

        void checkStructure(const BSONObj& spec, const DiskLoc node) const;

        bool isPresent(const BSONObj& key, int direction) const;

        static string expectedKey(const char* spec);

        OperationContext* _txn;
        BtreeLogicTestHelper<OnDiskFormat>* _helper;
    };

} // namespace mongo
